Message-Id:	<199701222148.WAA00572@math.amu.edu.pl>
Comments:	Authenticated sender is <grendel AT ananke DOT amu DOT edu DOT pl>
From:	"Mark Habersack" <grendel AT ananke DOT amu DOT edu DOT pl>
Organization:	What? (Poznan, Poland)
To:	Gene Buckle <geneb AT web DOT wa DOT net>
Date:	Wed, 22 Jan 1997 23:06:51 +0100
MIME-Version:	1.0
Subject:	Re: Passing a parameter to interrupt handler.
Reply-to:	grendel AT ananke DOT amu DOT edu DOT pl
CC:	djgpp AT delorie DOT com

Once upon a time (on 21 Jan 97 at 16:22) Gene Buckle said:

> > > Of all the great examples I've found for writing IRQ handlers, I've not
> > > seen one that documents how to pass a parameter (specifically a pointer
> > > to a structure) to the installed routine.
> > The only way I can see is through shared (and locked!) memory.
> 
> The whole program is locked in memory via the CRT0 flags.  My problem is
> that the program calling the interrupt (0xef in this case) won't be the same
> one that has the code for the actual ISR in it. ;)
Hmm... that changes things a bit. *If* your proggy will work under DPMI 1.0 
server and *if* the other program is guaranteed to use DPMI services, then 
shared memory is not a dream - you have it for free. If these conditions are 
not satisfied, you can provide a callback (say hanging on int2fh) that will 
pass the RM/PM address (as specified in registers on entry to the int2Fh 
handler) of the shared memory block you've allocated *from DOS* using DPMI 
services. Note that this memory has to come from DOS since it is not 
guaranteed that your "server's" memory will map 1:1 to DOS memory, and thus 
whether it will be accessible for other DOS apps or not. You pass the calling 
app a far pointer to the memory block (again RM/PM) and that's it!

> > _http://ananke.amu.edu.pl/~grendel_________________________
> > We buy fresh bagels from the corner store where swastikas
> > are spat from areosols. I sit in the bar sipping iced white
> > russians, trying to score but nobody's pushing. And everyone
> > looks at everyone's faces, searching for signs and praying
> > for traces of a conscience in residence, are we sitting on
> > a barbed wire fence chasing the clouds home?
> > 
> 
> You've got a collection of the oddest .sig quotes.... ;)
Thanks, I do my best! ;-) I'm constantly extending the set - they're going to 
be even more odd, I promise! ;-)

_http://ananke.amu.edu.pl/~grendel_________________________
We buy fresh bagels from the corner store where swastikas
are spat from areosols. I sit in the bar sipping iced white
russians, trying to score but nobody's pushing. And everyone
looks at everyone's faces, searching for signs and praying
for traces of a conscience in residence, are we sitting on
a barbed wire fence chasing the clouds home?

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